What's a flexitarian?

Most of us are omnivores, meaning we eat both a plant based and animal based diet.  Many studies have shown that eating an entirely plant based (vegetarian) diet is healthier than the average western diet, but it is usually too large a commitment for the average person.  A flexitarian is someone that eats a primarily plant based diet, but adds in small amounts of animal products.  But is this better than just a typical omnivorous diet (more balanced meat and plants)?